POSITION CONTROL OF A DC MOTOR USING PWM-PIM DIGITAL REDESIGN METHOD

Pulse-width modulation (PWM) is a commonly used technique in control of electric DC motors. PWM control systems have on/off control inputs with fixed amplitude and variable duty cycle. Here, a PWM control law is determined from a given discrete-time (DT) control law by applying the principle of equivalent area. An approach to the DT control system design is Plant Input Mapping (PIM) digital redesign, which gives a DT controller from a predesigned continuous-time (CT) controller. The PIM is a well-known digital redesign method which can guarantee the closed-loop stability for any non-pathological fast and slow sampling frequencies, has a superior performance even for low sampling frequencies, and is applicable to a variety of CT control systems. The proposed design method is applied to an experimental DC motor control setup to illustrate its effectiveness.